• Composites Research
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• v.13 no.1
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• pp.78-88
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• 2000

Tribological properties of fiber composite materials were measured and wear resistant hybrid structure was proposed based upon the understanding of tribological behavior of the composite materials. Unidirectional composites with glass fibers, carbon fibers, and aramid fibers were tested for tribological properties in order to propose a wear resistant hybrid structure. Hybrid composites which contain carbon and aramid fibers were prepared, the specimens were sliced by a water-jet cutter, and friction and wear properties were measured. An experimental set-up was designed and built for the friction and wear test of the composite specimens. Unidirectional fiber composite and hybrid composite specimens were tested to evaluated the tribological behavior for biomimetic applications. It is observed that the friction and wear behavior of fiber composites depends upon fiber orientation, sliding speed, and type of reinforcing fibers.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.285-293
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• 2009

Thermal infrared cameras have been conducted actively in various application areas, such as military, medical service, industries and cars. Because of their characteristic of sensing the radiant heat emitted from subjects in the range of long-wavelength($3{\sim}5{\mu}m$ or $8{\sim}12{\mu}m$), and of materializing a vision system, when general optics materials are used, they don't react to the light in the range of long-wavelength, and can't display their optic functions. Therefore, the materials with the feature of higher refractive index, reacting to the range of long-wavelength, are to be used. The kinds of materials with the characteristic of higher refractive index are limited, and their features are close to those of metals. Because of these metallic features, the existing producing method of optical systems were direct manufacturing method using grinding method or CAD/CAM, which put limit on productivity and made it difficult to properly cope with the increasing demand of markets. GASIR, a material, which can be molded easily, was selected among infrared ray optics materials in this study, and the optical system was designed with two Aspheric lenses. Because the lenses are molded in the environment of high temperature and high pressure, they require a special metallic pattern. The metallic pattern was produced with materials with ultra hardness that can stand high temperature and high pressure. As for the lens mold, GMP(Glass Molding Press) of the linear transfer method was used in order to improve the productivity of optical systems for thermal infrared cameras, which was the goal of this paper.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.553-553
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• 2000

The application as the parts of an automobile, using the property of GMT-Sheet, is increasing. In order to exchange the parts of an automobile for GMT-Sheet, at first, the establishment and joining problem of exact joining strength must be determined. We have studied it using composites which is not same each other fiber oriented condition so as to determine joining strength and joining condition of GMT-Sheet. h this study, the result of experiment of forming condition concerned joining problem of GMT-Sheet is this ; joining efficiency of of GMT-Sheet, increases as lap joint length L increases. Increase of compression ratio causes decrease of joining efficiency after of GMT-Sheet joining. In the viewpoint of recycling, randomly oriented composite of GMT-Sheet is desirable more than unidirectional oriented composite. We has better design the structure so as not to occur to stress centralizatien on the joining part.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.22-27
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• 2010

The usage of ultra-precision machining is increasing by the manufacturing of precision optical elements such as camera lens, laser printer, CD player, DVD and microscope parts etc.. The WC alloy material is in wide use by mold core to improve the productivity and accuracy in manufacturing those precision parts. The WC alloy mould core can be machined effectively by the parallel grinding process which is an excellent technique for manufacturing of surface profile hard to machining materials such as the hardened metal alloy, Ceramics, Glass and so on. Magnetic assisted polishing as a final polishing process has also been utilized to obtain ultra-precision mirror surface with the elimination of traces presented on ground surface. It is able to deduce the optimal ultra-precision machining conditions of the WC alloy material from the experiment and analyses results.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.111-119
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• 2001

The application as the parts of an automobile, using the property of GMT-Sheet, is increasing. In order to exchange the parts of an automobile for GMT-Sheet, at first, the establishment and problem of exact joining strength must be determined. We have studied it using composites which is not same each other fiber oriented condition so as to determine joining strength and joining condition of GMT-Sheet. In this study, the result of experiment of forming condition concerned joining problem of GMT-Sheet is this; joining efficiency of GMT-Sheet, increases as lap joint length L increases. Increase of compression ratio causes decrease of joining efficiency after of GMT-Sheet joining. In the viewpoint of recycling, randomly oriented composite of GMT-Sheet is desirable more than unidirectional oriented composite. We has better design the structure so as not to occur to stress centralization on the joining part.

• Food Science and Preservation
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• v.24 no.8
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• pp.1060-1066
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• 2017

This study was conducted to develop rice cookies added with young persimmon fruits. Effects of varying amounts (0-12%) of the fruit powder from a young astringent persimmon fruit (picked at July) on the quality characteristics of rice cookies were studied. Ingredients [rice (Oryza sativa subsp. japonica 'Ilpum') flours, persimmon (Diospyros kaki Thunb. 'Cheongdobansi') powder, sugar, butter, salt, baking powder, egg] were mixed, cut (thickness 3 mm, diameter 35 mm), baked at $170-180^{\circ}C$ for 9 min, cooled, and packaged in polyethylene/nylon bags. The loss rate and spread factor after baking of cookies increased and then decreased with an increase in the amount of fruit powder added. The moisture content and color values ($L^*$ and $a^*$) of cookies decreased with an increase in the amount of the persimmon powder added. Phenolic compounds content and DPPH radicals scavenging activity increased with an increase in persimmon powder content; in particular, the DPPH activity of the cookies sharply increased after the addition of 3% persimmon powder. These results suggest that the addition of the young persimmon fruit powder affected the quality characteristics of rice cookies and this fruit powder (approximately 3%) can be utilized as an additive during rice cookie processing.

• Polymer(Korea)
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• v.25 no.6
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• pp.803-810
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• 2001

A nonlinear optical hyperbranched polyester (PE-Azo/Hyper) was synthesized from 4-[N,N-bis(hydroxyethyl)amino-4'-formyl] azobenzene and cyanoacetic acid by a Knoevenagel polycondensation using 4-(dimethylamino) pyridine as a base. The resulting polymer was soluble in polar aprotic solvents such as N,N-dimethylformamide and 1-methyl-2-pyrrolidinone and could be processed into optical quality films by spin coating. The molecular weight was determined to be $M_w$=61,800 ($M_W/M_n{=1.86}$) by gel permeation chromatography using polystyrene as a standard. No melting point was detected by differential scanning Calorimeter, indicating that this polymer presents an amorphous state. It shows a glass transition temperature of $121^{\circ}C$. The second-order nonlinear optical coefficient $d_{33}$ of the poled polymer determined by the second harmonic generation at 1064 nm was 25.4 pm/V.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.4
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• pp.386-394
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• 2008

Osteosarcoma of the jaw is a rare malignant bone tumor which usually leads to a poor prognosis. It commonly occurs in young patients, especially in male. The tumor can involve mandible or maxilla with same frequency. The swelling in the involved area and facial deformity are common clinical findings. The pain and sensory changes are also complained by the patients. Although radical surgery plays an important role in the management of this tumor, the adjuvant chemotherapy or radiotherapy is used to enhance local control and to prevent distant metastases. We treated a 22-year-old male patient who had osteosarcoma in the left condylar region. The radical surgery which consisted of hemimandibulectomy and total parotidectomy, was done and an immediate mandibular reconstruction was performed with a vascularized free iliac osteomuscular flap. The obtained results, both esthetic and functional, were satisfactory. The patient was received postoperative chemotherapy. This is a case with reviews of the literatures.

• Clean Technology
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• v.24 no.4
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• pp.280-286
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• 2018

In this study, the adsorption performance of vapor phase VOCs under dry conditions was evaluated by using two metal oxides, $TiO_2$ powder and $Al_2O_3$ powder. BET analysis and ammonia in-situ FT-IR analysis were used to analyze specific surface area and surface acid site. As a result, $TiO_2$ powder and $Al_2O_3$ powder had a specific surface area of $317.6m^2\;g^{-1}$ and $64m^2\;g^{-1}$, respectively. In the case of $TiO_2$ powder, many acid sites were observed on the surface. As a result of evaluating the vapor phase VOCs adsorption performance using two metal oxide powders, $TiO_2$ powder having a relatively large specific surface area and a large number of acid sites exhibited relatively good adsorption performance. In particular, it is considered that the specific surface area directly affects the adsorption performance, and further study on the effect of the acid site is required. Based on the $TiO_2$ exhibited excellent adsorption performance, it manufactured into various forms of honeycomb, hollow fiber and disc. As a result, the adsorption performance was lower than that of the powder, but it is advantageous in view of applicability. In addition, it was confirmed that the disc adsorbent having excellent thermal durability due to the characteristics of the manufacturing process stably maintains adsorption performance even at a high temperature desorption process several times.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.101-106
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• 2020

In this study, epoxy-modified acrylate was synthesized. The synthesized acrylate was added to the composition for sheet molding compound (SMC) in the range of 5 phr to 15 phr. The prepared SMC prepreg was molded at high temperature and pressure to produce a glass fiber reinforced composite. Physical properties such as tensile and impact strength of the composite were measured, respectively. Experimental data show that the composite with 5 phr of synthesized acrylate has 20% improved tensile strength and 12% improved impact strength than that of the reference sample.